Constant velocity joints (CV joints) are used to transmit power between adjoining shafts at a constant velocity. CV joints are commonly used on vehicle drivetrain components such as the propeller shaft that transmits power between the transmission and the rear wheels, and the front half shafts of a front-wheel-drive vehicle. Common types of CV joints include a plunging tripod, a fixed tripod, a plunging-ball joint, and a fixed-ball joint. These common types of CV joints can be mono-block style or disk style.
CV joints are lubricated with grease and are sealed with a boot. CV joints are typically not serviceable and are lubricated at the factory for life of the part. The grease and the boot cooperate to lubricate the joint while keeping contaminants such as dirt and water out of the joint.
During operation, internal pressures are generated within the inner chamber of the CV joint. These pressures are vented to the outside air in order to prevent pressure buildup which may destroy the boot. Existing venting solutions include forming a hole in the grease cap to allow pressure to release from the inner chamber to the outside air. Because the hole is exposed to the elements, water and other contaminants may pass through the hole and into the inner chamber causing premature failure of the CV joint.
This disclosure is directed to the above challenges and other challenges as summarized below.